In general, the present invention relates to percutaneous transluminal devices and methods which are used treat obstructed (sclerotic) vessel lumina in humans. Furthermore, the present invention permits a continuous flow of blood during the procedure. In particular, the present invention relates to a perfusing sleevetballoon catheter apparatus which provides prolonged dilatations without blocking blood flow by use of passive perfusion.
Cardiovascular disease is commonly accepted as being one of the most serious health risks facing our society today. A blood vessel of the human circulatory system can often become narrowed whereby the flow of blood is severely limited. The location of the narrowed blood vessel is commonly referred to as the stenotic region and is generally caused by growth or hyperplasia of the surrounding vessel wall tissues sometimes referred to as atheroma. While the exact etiology of sclerotic cardiovascular disease is still in question, the treatment of narrowed coronary arteries is more defined. Surgical construction of coronary artery bypass grafts (CABG) is often the method of choice when there are several diseased segments in one or multiple arteries. Open heart surgery is, of course, very traumatic for patients. In many cases, less traumatic, alternative methods are available for treating cardiovascular disease percutaneously. Balloon angioplasty is accepted as an efficient and effective method for treating types of vascular diseases. In particular, balloon angioplasty is widely used for dilating stenotic regions in coronary arteries, although it is also used for treatment of stenoses in other parts of the vascular system including the peripheral vessels of the legs and kidneys and the carotid arteries in the neck. The most widely used form of balloon angioplasty is percutaneous transluminal coronary angioplasty (PTCA) and makes use of a guidewire, guide catheter and dilatation catheter which has an inflatable balloon at its distal end. Using fluoroscopic control, the physician first positions a guidewire to and beyond the stenotic region of interest. The physician then threads the catheter over the guidewire, advancing it through the vascular system until the distal balloon is positioned across the stenosis. The balloon is then inflated by supplying fluid under pressure through an inflation lumen in the catheter body. The expansion of the balloon dilates the vessel typically reestablishing acceptable blood flow through the vessel. Often balloon angioplasty is followed by the implantation of a stent to maximize and maintain the vessel patency after primary dilatation.
An initial concern about PTCA was the temporary blockage of blood flow during balloon inflation caused ischemic conditions distal to the balloon. As cardiologists gained clinical experience with PTCA, it became common knowledge that the vast majority of patients tolerate 30 to 60 second dilatations quite well. Concurrently, cardiologists discovered that prolonged dilatations can help overcome certain kinds of complications encountered with the angioplasty. Prolonged dilatations of several minutes are used to deal with dissections, perforations, intimal flaps, acute thrombosis and vessel spasms. The profound ischemia of a long dilatation is outweighed by the potential prevention of emergency coronary bypass surgery or the expense of deploying a permanent stent.
In the prior art, methods for enabling prolonged dilatations have been cumbersome, have been experimental, or have had potentially harmful side effects. Consequently, there has been no definitive study of the effects of prolonged dilations on the efficacy of PTCA.
In order to perform prolonged dilatations, several approaches have been suggested. These include the use of pharmacologic agents to improve myocardial tolerance of ischemia, synchronized retroprofusion, mechanical pump distal perfusion, and auto or passive perfusion.
The use of pharmacologic agents treats the symptoms of ischemia, but not the cause. As a result, this approach is inherently limited.
Synchronized retroprofusion involves pumping blood during diastole into the coronary sinus and then sub-selectively into the regional coronary veins which drain the jeopardized myocardium. This approach potentially offers nearly complete myocardial perfusion. The disadvantage of synchronized retroprofusion, however, is that it is complicated and cumbersome.
Mechanical pump distal perfusion involves pumping blood (or other perfusate) through a lumen of the PTCA catheter. The need to pump through the PTCA catheter requires some form of mechanical pump, and complicates the angioplasty equipment and procedure.
With passive perfusion, the balloon catheter acts as a temporary stent. Passive or auto perfusion catheters which have been proposed in the past have used a design similar to xe2x80x9cbail outxe2x80x9d catheters. On group of passive perfusion devices incorporate side holes in the catheter through a defined lumen proximal and distal to the balloon. These catheters, however, have several limitations. First, blood flow through the balloon may be suboptimal for many clinical situations (such as distal lesions and hypotension). And second, this configuration usually requires that the guidewire be retracted from the catheter lumen to maximize the flow of blood.
The perfusion sleeve/placement catheter assembly of the present invention includes 1) a perfusion sleeve apparatus having a multiple lumen shaft and an perfusion sleeve connected to a distal end of the shaft and 2) a placement catheter having a multiple lumen shaft and an expanding balloon connected to a distal end of the shaft.
The perfusion sleeve comprise a composite balloon including a semi-rigid inner material surrounded by a more flexible and expandable outer material which can extends radially from the catheter and engage the vessel wall and/or atheroma. The semi-rigid inner material requires more pressure to cause distention than the outer expandable material. When fluid is injected to fill the cavity defined by the joined outer and inner materials, distention of the outer balloon material exerts pressure to the wall of the vessel resulting in an angioplasty dilation while the inner balloon material resists distention and maintains a blood flow lumen. The perfusion sleeve can include a means attached and located on the outer balloon material to cooperated with a separate guidewire.
The placement catheter apparatus comprises a multiple lumen shaft with a standard expandable balloon connected to the distal end. The placement balloon is inflated to engage the inner material of the composite sleeve balloon to 1) facilitate placement of the assembly into vessel segment 2) to provide support to the inner material of the composite balloon to minimize distension into the blood flow lumen during inflation of the sleeve""s composite balloon, and 3) to assist in the removal of the perfusion sleeve from a vessel segment. When the balloon of the placement catheter is deflated, it can be removed from the perfusion sleeve and retracted along the guidewire. When the placement catheter is retracted, the perfusion sleeve defines a longitudinal channel through which blood can flow. The balloon on the perfusion sleeve can be inflated prior to retraction of the placement catheter to restrict migration of the perfusion sleeve within an arterial or venous segment. The blood flow channel is generally aligned with a longitudinal length of the sleeve apparatus and in the preferred embodiment, the guide wire from the placement catheter extends through the sleeve lumen and out the distal end. The placement catheter also can comprise a rapid exchange design.
In operation, the balloon on the perfusion sleeve is deflated with the placement catheter balloon partially inflated to engage the inner surface of the perfusion sleeve but not fully to minimize the overall profile. The over-the-wire embodiment is advanced over a previously placed guidewire until the assembly is located within the desirable vessel segment. The placement catheter is then fully inflated. The expandable outer portion of the perfusion sleeve is inflated to maximize the engagement with the vessel wall performing a angioplasty dilation. The placement catheter is then deflated and retracted from the lumen of the perfusion sleeve. Blood is allowed to perfuse through the blood flow lumen of the perfusion sleeve for long durations.
When removal of the perfusion sleeve is desired, the placement catheter is advanced, with the distal balloon deflated, until it becomes centered within the perfusion sleeve. Radiopaque markers are provided on both the perfusion sleeve and in the balloon of the placement catheter to assist in identifying proper alignment and insertion of the assembly. When proper alignment is achieved, the balloon of the perfusion catheter is re-inflated and the expandable portion of the perfusion sleeve is deflated and the placement catheter/perfusion sleeve assembly is retracted and removed from the blood vessel as a unit.
It is an object of the present invention to be used as a routine angioplasty catheter to decrease a stenosis within a blood vessel but at the same time permitting much longer dilation time without the occurrence of ischemia events.
It is another object of the present invention to provide a gradual increase in dilation pressures without a significant decrease of blood flow thereby decreasing vessel wall injury or complications such as dissection, perforation or vessel trauma.
It is another object of the present invention to provide a longer dilation time to decrease the incidence of xe2x80x9creboundxe2x80x9d phenomena.
It is another object of the present invention to provide a longer dilation time to alleviate complications such as dissections and flap formations allowing normal tissue glue and normal processes to repair the vessel.
It is another object of the present invention to decrease the general the use of anticoagulants associated with the angioplasty procedure.